A camshaft for use in an internal combustion engine of a type having spring loaded cam followers experiences a series of oppositely directed torque pulses during each revolution of the camshaft. The positive-going portion of each pulse occurs as a result of the need to apply torque to the camshaft to cause each of its operating cams to rotate against the force of the cam follower during the opening of the valve which is operated by such cam follower, and the negative-going portion occurs as the result of the application of an oppositely directed torque to the camshaft as the operating cam resists the force of the cam follower during the closing of the valve.
The resulting torque pulses can be used for actuation purposes, e.g., as a means for providing a control signal to a variable cam timing system (VCT) as disclosed in U.S. Pat. No. 5,002,023. The present invention incorporates by reference the disclosure of said U.S. patent.
For certain applications (usually inline 4-cylinder and 6-cylinder engines), however, the torque pulses may not be of sufficient magnitude for actuation of a VCT system according to U.S. Pat. No. 5,002,023. In these cases the torque pulses must be amplified to be utilized effectively.